Kerzner says buys for this season happened last January, so they won't be able to produce and ship any more costumes for this Halloween.

"We work about a year in advance, so we are starting to sell for 2013 right now," she says. "It's gonna be hard. People will be disappointed because they can't get the costume. You are going to find people selling them on eBay."

Big Bird hopefuls might have to make their costumes themselves because more readily available unlicensed costumes, produced by someone other than Disguise, could also be on their way out of reach.

"The only costumes authorized by Sesame Workshop are with our licensee, Disguise, and we are working with our legal team on having the others removed from the market," said Ellen Lewis, a spokeswoman for Sesame Street.

Despite the dearth of costumes, people are still out shopping with big yellow hopes.

Halloween Adventure in New York City sold out of the costumes immediately after the first debate, but people continue to come in asking for Big Bird.

"We have all the other Sesame Street characters, but everyone only wants Big Bird," cashier Tiffany Padua says. "We have just been telling people, 'Buy the Mitt Romney mask and put a beak on it.' "